During recent years, technology has provided for the ever-decreasing size of office products and personal communications systems (PCS). Devices such as laptop computers, personal digital assistants (PDA) and cell phones continue to become both lighter and smaller. Although the market demands a wireless network to connect these devices, certain technical challenges exist in the optimization of such a network. One of these challenges is the miniaturization of the antenna to be mounted to these devices.
For example, a conventional microstrip antenna designed to efficiently radiate at 2.4 GHz would require an antenna patch (radiating element) in the order of 6.25 cm. This dimension does not include the ground plane, which would extend this dimension further.
There are two basic parts of an antenna and therefore two basic considerations when reducing its size; the size of the radiating element and the size of the ground plane. The radiating element receives and transmits the electromagnetic signal, while the ground plane is required to reduce the effects of back lobe radiation, to lessen impedance variation, and to maintain the gain and the bandwidth. Most conventional methods of antenna miniaturization (such as shorting pins, slotting, and the use of high dielectric substrates) have focused on the miniaturization of the radiating element itself. While these methods have been effective, increased space considerations demand still further size reduction.